【作者】 袁宇；

【导师】 翁杰；

【作者基本信息】 西南交通大学 ， 材料科学与工程， 2009， 硕士

【摘要】 骨组织工程支架作为组织工程学的一个分支得到了广泛的研究和发展,它为解决和改善治疗人们生活中的骨缺损、骨修复提供了新的思路,带来了新的希望。在骨组织工程支架的研究中,支架材料的选择是关键因素之一;大量研究表明可作为骨组织工程支架的材料种类很多,它们都必须具备的共同特点是:良好的生物相容性(无毒、不致畸、无炎症反应等),良好的生物降解性(降解可控),适宜的力学性能(满足实验所需),良好的材料表面微环境(微孔和粗糙程度等)。而支架的形貌和结构又直接影响着它的功能,随着研究的不断深入,对支架的要求也越来越具体:良好的三维贯通性,高的孔隙率,合适的孔径大小,均匀的孔隙分布,高的比表面积和结构可控、便于重复等等。为了满足这些要求,各种各样的支架制备方法被应用于实际,但是到目前为止,还没能找到一种简单易行、经济实惠的制备方法。以此为出发点,本论文进行了下面的探索性实验。实验中选取以羟基磷灰石(HA)为原料:它属于生物陶瓷,其化学成份和晶体结构与脊椎动物的牙齿、骨组织中的无机成分相似,具有优良的生物亲和性,与骨组织极易结合,生物相容性好,更重要的是对人体组织无任何的毒副作用。实验中采用球粒堆积的方式制备了新型的多孔陶瓷支架,为考察该支架体系的生物活性,以动物狗为对象进行了体内非骨部位的诱导成骨性能研究,并取得了满意的实验结果,其主要结论如下:1.采用溶胶-凝胶法和W/O乳化成球技术制备了多孔的HA球粒,并对其形貌结构进行了表征。结果显示:该方法制备的多孔HA球粒粒径分布均匀,球粒的粒径可通过搅拌的速率来调节且与搅拌的速率成反比,球形度优良,具有很好的力学性能和高的比表面积,单颗纯HA球粒的孔隙率分布在15%～20%之间。通过添加不同制孔剂的方法可以改变球粒内部的孔隙大小和孔隙形貌,并可以提高单颗球粒的孔隙率,平均值最高可达到30%。2.采用有机泡沫模板法制备了多孔HA网管和盖子,通过球粒堆积的方式制备了新型的三维多孔圆柱状支架,赋予了其规整的外形,优良的三维贯通性和高孔隙率(平均分在布48%～66.9%左右,最高可达到70%)。该支架主要优点在于:支架结构、孔隙结构可控,孔隙大小分布广泛,微孔和宏孔相结合,孔隙形貌特别且可调。3.在动物狗体内四个不同的非骨部位对支架的异位诱导成骨能力进行了研究,具体部位为腹腔内大网膜包裹(AC)、壁层腹膜内(P)、股部肌肉(M)、股骨旁骨膜覆盖(FP)。体内实验结果显示:在未载入任何生长因子或药物的前提下,六个月时,本支架体系表现出良好的异位骨诱导性:在部位P和M的支架,微球间骨基质生长良好,血管生长丰富,有大量成熟的骨细胞镶嵌在骨陷窝上;而在FP部位的支架是生长情况最好的,可以明显的见到骨组织生长优异且有片层状的新骨长成。这说明该支架孔隙结构合理,孔隙大小适宜,利于细胞的粘附生长和新生血管的长入,为组织液和氧份等提供了便捷的通道,有利于新陈代谢。在相同时间下,种植在AC部位的支架内血管生长数少,管径小,也未见到明显的骨基质生长。不同非骨部位的结果反应出支架的异位诱导能力跟种植的部位密切相关,且支架在植入前期的内部血管化程度是影响支架异位诱导能力的一个至关重要的因素。综合分析,在本实验中,支架在同物种不同非骨部位诱导成骨能力的强弱顺序排列如下:FP＞P=M＞AC。更多还原

【Abstract】 The scaffold of bone tissue engineering as a branch of tissue engineering was got a broad study and development, it could be offer some new ideas and bring some hope for solving and improving the therapy of bone repair and replacement in people’s daily life. In the study of this field, kinds of material is the key factor. A lot of study indicate that many kinds of materials can be used in bone tissue engineering, but they must have the co-characteristics: be good at biocompatibility (innocuity, no-teratogenesis, no-inflammation response etc), biodegradation (the velocity of degradation can be controlled), micro-environment of material’s surface (include microporous and roughness) and mechanical property (to gratify the need of experiment). On a certain extent, function of the scaffold is influenced by its shape and structure, therefore, more and more idiographic requirements can be proposaled in the interest of improving capability of it. For instance: three-dimensional interconnection, high porosity and specific surface area, pore size and distribution, can be controlled and repeated easily. In order to satisfy this requirements many methods of fabrication scaffold were used in practice, but, up to now, people are much to seek a sort of preparation method which is simpleness and economy. At beginning of this, we put up a exploring experiment in this paper.Hydroxyapatite (HA) belongs to bioceramic is performed in this study because its chemical composition and crystal structure is extraordinary similar with inorganic in dens and osseous tissue in vertebrate, which with excellent biocompatibility and combine with osseous tissue easily. A novel porous bioceramic scaffold is prepared by accumulating HA spherules and in order to study ectopia osteoinduction of the scaffolds in vivo which were implanted in four different non-osseous sites in dogs. At last, we get a useful and satisfying results, the main conclusions are drawn as follows:1. Fabrication porous HA spherule by the method of sol-gel and water/oil emulsification technology. Results of characterization reveal that: porous HA spherules with a high specific surface area, a appropriate mechanical property and excellent sophericity, pores size is inverese ratio to stirring speed and porosity of HA spherule in the scope of 15% to 20%, micropores size and shape can be changed by pore-maker, under this conditions, porosity of HA spherules can be arrived at 30% in max.2. Method of polymer sponge template is used to preparation porous HA tube and discs, and a novel three-dimensional porous bioceramic scaffold called the HA spherule scaffold with regular shape, excellent interconnection and high porosity (average is in the scope of 48% to 66.9%, the max. can be up to 70%) manufactured by accumulating HA spherules. The great advantages of this scaffold are the controlled interconnection of pores, the adjustable microstructure of HA spherules and the easy reconstruction of porous structure.3. To study a ability of osteoinduction of the scaffolds which were implanted in four different non-osseous sites in dogs: in abdominal cavity (AC), peritoneum pocket (P), muscle (M) and beside the femur (FP). Samples are collected after six months and the results indicate that: the HA spherule scaffold can induce angiogenesis and bone formation without use of cytokines for vasculogenesis or bone-induction. There were not only a mass of blood vessels appeared and a lot of mature osteocytes inlayed on the bone lacuna but also the bone stroma grew well and a plenty of collagen fibres filled in it appeared around the spherules while speciments implanteded in P and M, and when the speciments in FP the growth conditions is the best that the osseous tissues developed quite perfect and the newly-formed bone even had a lamellar structure with many mature osteocytes. So, these proved that this scaffold have a reasonable pore structure, pore size and porosity, which in favor of attachment, differentiation and proliferation of cells, provide a convenient channels to transport tissue fluid and nutrient, speed up metabolism. In contrast, there were a small quantity of blood vessels and almost no newly formed bone in the specimens implanted in abdominal cavity while a few of collagen fibres around HA spherules. Different results reveal that ectopia osteoinduction is directly attached to the site of non-osseous and the degree of vascularization in prophase is a vital importance to osteoinduction. In this study, the sequence of osteoinduction ability at the four different non-osseous as follows: FP > P = M > AC.更多还原